U.S. Pat. No. 4,247,605, Paquette, discloses a method of forming and starting a sodium sulfur battery when heated to a temperature suitable for battery operation. Similarly, U.S. Pat. No. 4,226,923, Mikkor, discloses a method of forming a volume efficient sodium sulfur battery.
Existing liquids and pliable solid sheet materials will degrade thermally at an unacceptable rate in this environment. Furthermore, many of the existing materials are combustible in air at the battery operating temperatures. Therefore, there is a need for inert, electrically resistant materials stable in the higher temperature battery environment.